Not been to CATS, but from my experience, even if you had a week intensive study, you'd be hard pushed to complete all the exams.
Human Performance is pretty simple, you can pass that with an afternoon of study, but Met/Nav are a different kettle of fish, and Nav becomes much more obvious once you've done some real life cross country work.
Air Law is a memory job, and will take time to sink it - it's also important stuff as you'll need it when you fly, and will need it to go solo.
A week's course would probably be an ideal referesher/supplement, but I think you'd need to hit the books far in advance to pass the exams competently. The Nav/Met/Air Law books will take a week to read through each if nothing else!
However - not been to CATS - so don't know.